binoc_filter

Overview

This model implements the basic binocular disparity energy (BDE) model of
Ohzawa et al. (1998), as well as variations on this model proposed
by Chen et al. (2001) and Read et al. (2002).

Configuring the Model

Parameters

These parameters set the basic simulation settings:

sscale - spatial resolution (degrees/pixel)

tscale - temporal resolution (samples per second)

xn - filter x-axis spatial extent (pixels)

yn - filter y-axis spatial extent (pixels)

tn - duration of the model (sampling units)

The following phase parameters are common to all BDE models and set up the
spatial phase shift between the left and right eyes. Note that in WM, the
negative spatial filters are inferred (we do not have explicit parameters
for setting the -1s/d or -2s/d pathways).

phase_1 - Spatial phase of cosine in Gabor for first left filter

phase_shift - Spatial phase shift of right eye RF relative to
phase_1

The next 2 options are implemented for defining the 4 subunit filters in
the BDE models. ME models are always in a specific quadrature relationship
(+90 deg) by convention, but this can produce incorrect filters for the
Read et al. models depending on which type of disparity tuning is being built
(ie. TE/TI vs NE/FA).

quad_shift_opp - [0,1] -- if 1, use -90 deg quadrature shift
instead of +90 (2s to 2d). This is allows a variation on quadrature from
the ME models, where the quadrature shift is always +90 degrees (ME model
we define 1s to 1d shift as +90, 2s and 2d are then adjusted to give
anti-direction RFs)

The following parameters relate to the last two stages of the BDE model,
introducing options for rectification and inhibitory interactions
as in the Read et al. models. In particular, 'right_sign' sets the
pattern of +'s and -'s that indicate addition or subtraction of each
subunit output.

Filters

binoc_filter models use a <filter>
object that specifies parameters for the spatiotemporal RFs of each monocular
subunit. For the BDE_Gabor and BDE_Gabor_DS models as well as the BDE_RPC
models, the basic 'Gabor' filter is used. With the BDE_CWQ models,
a specific 'Gabor_CWQ' filter type is defined, that includes parameters
for the temporal filtering implented in the Chen et al. models.

Spike Generation

binoc_filter models also require a
<spike_gen>
object that defines the method of spike generation from the final filter
output.

Model Outputs

Model Components

The spatial filters for each of the four component monocular subunits can be
output using the <filter> object's write_filter option.
If Poisson spike generation is used, then the output firing probability
can be written to a .pl file using the spike_dump option in
<spike_gen>.

Model Responses

The following response types can be requested:

spikes - spike times

binoc_energy - final stage filter output

binoc_1 - input to final stage from pathway 1

binoc_2 - input to final stage from pathway 2

filter_left_1 - output from subunit 1s

filter_left_2 - output from subunit 2s

filter_right_1 - output from subunit 1d

filter_right_2 - output from subunit 2d

binoc_1_pos - summed output from 1s and 1d

binoc_1_neg - summed output from -1s and -1d

binoc_2_pos - summed output from 2s and 2d

binoc_2_neg - summed output from -2s and -2d

binoc_1_pos_sq - binoc_1_pos signal squared

binoc_1_neg_sq - binoc_1_neg signal squared

binoc_2_pos_sq - binoc_2_pos signal squared

binoc_2_neg_sq - binoc_2_neg signal squared

A template .rsp file including these quantities can be downloaded
here.